1. Technical Field
The present invention relates to a control device of a motor, an electronic apparatus, a recording apparatus, a robot, and a control method of a motor.
2. Related Art
A stepping motor is a synchronous motor that rotates a rotor by a magnetic flux which is generated by supplying an excitation current to a coil provided on a stator. Positioning control in which the rotational angle of the rotor is determined according to the number of an input pulse is easily performed in the stepping motor and the stepping motor is often driven by an open-loop control.
However, when driving at high speed or driving with a heavy load, deviation occurs between a target position (command position) and an actual position of the rotor, and then stepping out may occur.
Thus, in the stepping motor, in order to prevent stepping out, a feedback control may be executed based on a position of the rotor. A technique is disclosed in Pamphlet of International Publication No. 00/004632, in which positions (in other words, a position of the rotor) of the magnetic poles provided in the rotor are calculated based on a value of a counter-electromotive voltage induced in a coil by rotation of the rotor.
However, a magnitude (absolute value) of the counter-electromotive voltage induced in the coil by the rotation of the rotor is dependent on the speed of the rotor. Specifically, if the speed of the rotor is decreased, the counter-electromotive voltage is also decreased. Thus, if a rotational speed of the rotor is low, the counter-electromotive voltage is too small and the position of the rotor may not be appropriately calculated. As described above, precision of the calculation of the position of the rotor based on the value of the counter-electromotive voltage is not high.
Moreover, it is possible to specify the position of the rotor with high precision by providing a sensor that detects the position of the rotor. However, a configuration in which the sensor is provided is not preferable in view of the miniaturization or cost of the apparatus.